Wind turbine blades are often made of fibre reinforced polymer materials. In the manufacturing of such blades often two elongated blade shell moulds placed side by side are used, whereby material is placed in them, the material is cured, and then one of the moulds is turned over the other one. The turning can be done with the cured blade shell material, and usually a connecting structure, such as a spar or a pair of webs, is placed so as to be bonded internally between the shells when the mould has been turned. The turning is usually effected by a turner mechanism connecting the mould halves and comprising drive units and turner arms which swing one of the mould over on top of the other one.
Due to the significant length of many modern wind turbine blades, the use of a gantry system for transporting material to the moulds and placing material in the moulds can be advantageous, and it has been suggested e.g. in DK200400032U3 and WO2007/054088A1. Such a system typically involves one or more movable parts in the form of gantry cranes, each extending transversaly over one of the moulds, which cranes can carry rolls of material, spray equipment, robots or human interface controlled devices. The gantries are supported by elongated support members in the form of rails extending parallel to the moulds and on either side of them. Further the gantries are arranged to move along the mould and to be positioned at any location along the moulds by being driven and guided along the rails.
A problem occurring in production apparatuses of the type described above is interference between the turner arms and a centre rail of the gantry system located between the moulds. In this respect WO2011/035539 describes an automated production system for wind turbine blades. To solve said problem, the centre rail comprises gaps that are positioned such that the turner arms can move through the corresponding gaps when closing the mould. In the open position of the mould assemblies the gaps may be “bridged” by a specific wheel system on the gantry that allows the crossing of the gaps without losing contact to the centre rail. As an alternative it is suggested to close the gaps for gantry use by bridge sections, which are removed for passing of the turner arms. Although the production system described in this document may provide for certain advantages with respect to allowing access of the moulds, there is still room for improvement so as to solve said interference problem in a manner that retains a high degree of structural integrity of the apparatus.